The present invention relates generally to an optical character reading system (OCR), and more particularly pertains to improvements in a character recognition and identification system where inherent characteristic of respective characters are determined and sensed in order to provide the identity of the respective characters by utilization of constraining dots and radius vectors.
The article "Reading Handwritten Characters" by Dimond, T. L.: Bell Laboratories Record, Jan. 1958, pp 34-35, discusses a method of reading and recognizing handwritten characters of a type of interest in the present application. As illustrated in FIG. 1a, pursuant to teachings of Dimond's method there were provided 2-dot constraints 1a, 1b to guide the formation of characters to be handwritten and a predetermined number (seven in this instance) of radius vectors Za, Zb, Zc, Zg, Zh, Zi and Zj which extend out from each of these constraining dots 1a, 1b. The respective characters are identified by combinations of crossings where these radius vectors are crossed by that character since each of the characters has a unique set of crossings. By way of example, the character "5" is recognized and identified as below. EQU "5"=Za.multidot.Zb.multidot.Zc.multidot.Zg.multidot.Zh.multidot.Zi.multidot .Zj (1)
The above discussed method has the advantages of being simpler in construction and design than any other recognition method.
Such a method, therefore, has been employed over a wide range of OCR's. In practice, such a method is accomplished by sampling and normalizing the characters in the well known segmented font (for example, such as the seven-segmented font made up of seven segments Sa, Sb, . . . Sj as depicted in FIG. 1b) rather than recognizing the inherent characteristics of the respective characters.
The handwritten characters must be restricted in their size and form by means of the constraining dots 1a and 1b and outline 3 and be marked on a suitable medium such as a ticket in accordance with the typical pattern examples illustrated in FIG. 2a. Nevertheless, the handwritten characters thus obtained vary in size and form due to individual differences.
For example, as suggested in FIG. 2b no distinction between the characters "4" and "9" will be sensed to provide a possibility of error, and the character "7" will be vague and undefined for recognition and identification requirements. Although the characters "6" and "9" are distinguishable, their humming distance to the character "8" is only one thereby providing a possibility of misjudgement.
Accordingly, auxiliary characteristic recognition methods such as geometrical characteristic recognition as to the crossings and loops of the respective characters have been proposed to overcome the shortcomings set forth above. These methods, however, need a discrete circuit arrangement and render their implementations complex.
In addition, as illustrated in FIG. 2c, a more powerful approach has been suggested, which approach employs four constraining dots 1a, 1b, 1c and 1d within the outline 3 for constraining more severely the formation of the handwritten characters, thereby alleviating individual differences. This does not permit the formation of the smaller characters and hence improvements in information density of the medium.